Notes : Alethopteris was the main genus of the famous “seed ferns” which populated the Carboniferous period. It could grow like a shrub or a small tree. The seed ferns featured distinctive fronds whose parts looked more like some of today’s broadleaf leaflets than they look like today’s ferns’ fronds. But mostly, it’s the seed “cones” they used to bear which make them look unique compared to today’s ferns. All seed ferns are long-time extinct.